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Aseptic Peristaltic Pump Design Jason Binz Matt Giordano Craig Lebro Alex Reeser Scientific Products & Systems, Inc
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22 About SP&S Scientific Products and Systems, Inc. Specialize in high precision pumping systems – Used for Pharmaceutical, Specialty chemicals and other precision pumping applications OnePump®, OneBloc® systems – Positive displacement pumps – Peristaltic Pumps http://www.spspump.com/
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33 Project Scope SP&S feels a reusable, high precision pump will launch company to top of market for pumping specialty chemicals Design a new pump for integration into existing OneBloc ® and OnePump ® system Retain the high precision found in existing pumps http://www.spspump.com/
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4 Considerations for Design Designer drugs lead to problems with cleaning – Autoclave – Vaporized Hydrogen Peroxide Previous assembly usually discarded if the tube breaks Limit number of tools for head removal
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55 What is a Peristaltic Pump? Positive Displacement Pump – Used for high precision/low volume pumping – Benefits Only tubing comes in contact with fluid Very accurate volume control – Only limited by motor and torque transmission to head – Downsides Tube breakage if not maintained properly Can lose precision with pumping due to wear in tube
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66 SP&S Wants for New Design Precision pumping – Utilize existing micro stepping drive system Capable of at least 51,200 steps for ultra-high precision Needed for pumping small volumes Head Design – Single tubing Allows for tube to be advanced when worn Capable of placing tube above and below rollers – Allows for alternating pulses Holders to maintain tension in tubing – Rollers PEEK material, Odd number – Stainless steel pressure shoes
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77 Design Metrics Metrics determined from SP&S wants and restrictions Used to compare different design concepts
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88 Subsystem Design Adjustable height Cam Cleat Spring Clamp Fixed Lever Controlled Spring Clamp Bar and Latch Gear Clamp Cam-Follower Tube Tensioner Shoe Design Square with rounded ends Star Pattern Square Threaded Clasp Half Circle Aseptic Peristaltic Pump Head Tube Tensioner Shoe Design Roller Head Shaft Spring Clasps
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99 Shaft Geometry Used precision comparison to narrow down to two shaft geometries – Both give excellent torque transmission Spline Squared-off round shaft Square-off round chosen – Less recessed surfaces – Makes it easier to clean with vaporized hydrogen peroxide – More difficult to manufacture, but better satisfied design metrics
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10 Roller Head Circular head – Easily manufactured – Allows for varying number of rollers – Held on by Knurled nut to be tightened by hand Rollers – PEEK rollers – Range from 3-7 rollers Less rollers for higher volume displacement Still maintain accuracy and precision of pump Combination of roller and head materials chosen to satisfy autoclave metric All components easily taken apart to ensure thorough cleaning
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11 Shoe Design Adjustable Shoe Height – Allows to use range of tubes and maintain precision Comparison of different designs to hold shoe to cover plate – Bail Latch Difficult to clean mechanism Uneven wear in latches can lead to uneven pressure across shoe and decreased precision – Cam Latch Easily cleaned in autoclave Little wear – Maintain constant shoe force after repeated use Easily latches to center base without tools Center piece holds top and bottom shoe as well as tube – Stainless steel so that it can be autoclaved Top and bottom shoe could discarded in event of tube breakage Cam Latch was chosen since it satisfied more design metrics
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12 Prototype Shoe Assembly Cover plate put over roller head Tubes placed in grooves Clamping plates slip into place Shoes slide in and lock into place using cams Use wing nut to adjust spring tension if needed
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13 Tube Tensioner During pumping – Tube stretches After pumping – Tube experiences elastic recoil For low volume dispensing, this can cause large discrepancies in precision – Tensioner used to prevent recoil to maintain precision Final decision was to use compression fittings with spring tensioners – Cheap enough to discard if tube breaks – Easy to disassemble to advance tube – Ensures desired precision Compression fitting holds tube on other side Spring will have protective jacket on inside to prevent damage to tube
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14 Final Design Concept Proposal Due to Cams, head mounted horizontally
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15 Attach Roller HeadPlace Cover OnPlace Tube In Slot Slide Shoes in PlaceClamp Shoes to Cover PlateFinal Prototype Final Design Concept Proposal
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16 Cost Analysis Senior Design Aspect Prototype Costs – $2,000 – Covers: all prototype materials test stand Motor Final Production Approximate Product Costs – With Motor $2,800 - $3,300 – Without Motor $2,000 – $2,500 Replacement Parts – $150 - $200 – Covers cost of replacement package for discarded parts Tubing and Tensioners Springs and Shoe Parts 16
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17 Testing Plan Based on Metrics MetricPlan Dispensing PrecisionMeasure mass of displaced volume Autoclave SurvivabilityType of materials and autoclave test Disassembly TimeTime the disassembly Tension in TubeVisually inspect for “suck-back” in tube Contact Force on Rollers Under – Liquid continue to flow Over – Strain on motor Variable VolumesAbility to operate over wide range of tube sizes
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18 Concept Validation Tube Sizes Precision Testing 3 mL Dispensing Test Average [mL]Standard Deviation [mL]Relative Standard Dev. [%] Small (Slow Speed)3.01500.06832.26 Small (Fast Speed)2.99320.06332.12 Medium2.98320.15485.19 Large3.00630.01140.38 5 mL Dispensing Test Small5.10500.11592.27 Medium4.99010.03810.76 Large4.98930.08361.68 10 mL Dispensing Test Small9.99190.12161.22 Medium10.00640.125701.27 Large10.03920.06350.63 SmallMediumLarge 3.2 mm ID6.4 mm ID9.6 mm ID
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19 Concept Validation
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20 Concept Validation
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21 Concept Validation
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22 Visual Observations Precision not achieved due to prototype machining – Parts were modified to be assembled Allowed for shoes to travel and shaft raised slightly during testing – Manufacturing processes can be changed to increased precision and reduce shoe movement Tube Tension – Saw visual suck-back Not enough tension on tube Need to modify tube tensioner to keep steady pressure Shoe Pressure – Adjustment nut allowed to shoes to be raised or lowered to achieve optimal pressure
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23 Disassembly Time Average disassembly time for group members – 28.62 s Average disassembly time for test subjects – 44.59 s Overall Average – 36.60 s Test group was large enough to determine the target value of <1 min was achieved
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24 Manufacturing Plan Shoe Casing and Supports – Molded Roller Head – CNC/Water Jet Rollers and Shaft – Lathe or Extrusion Tensioner, Height Adjustor, Motor – Purchased Parts
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25 Integration in SP&S Product Line OneBloc ® System – Pump designed to be easily integrated into this system – Replaces current design with only modification in attachment point OnePump ® – Currently has vertical arrangement – Need to add gear box to achieve the horizontal design Both can be achieved simply with little modification, additions, or costs
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26 Acknowledgements SP&S – Mr. David Bach – Mr. Milton Cochran – Mr. Ronald Genova – SP&S Staff – Tom Cassidy University of Delaware – Dr. Robert Hartman – Mr. Steve Beard – Mr. Roger Stahl – Senior Design Advisors
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27 Detailed Project Costs 27
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28 Detailed SP&S Prototype Costs 28
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29 Detailed Production and Replacement Costs 29
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30 Alternative Tube Tensioner Cam Cleats – Allows for one tube to move in one direction Spring Clamp – Hold tube in place Design – Either use cam cleat on both sides or on one side – Thoughts? http://www.petticrows.com
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31 Alternate Shoe Designs Cam follower Lever Controlled Spring Clamp
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32 Completed Tasks to Date
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33 Future Tasks Tasks that still need to be completed
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34 Phase 1 Completed Task Schedule
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35 Phase 2 Completed Task Schedule
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36 Phase 3 Completed Task Schedule
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37 Phase 4 Future Work
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